Devices for visualizing wind currents and other types of airflow are known. In a common arrangement, a resiliently deformable bottle carries a fine powder material, and the user squeezes the bottle to discharge a puff of air including the visible powder material into the atmosphere. The powdered stream of air may be viewed by the user as it is acted upon by wind currents or other localized airflow, thereby providing the user with a visual indication of the direction and strength of such airflow. Examples of powder discharge visualization devices are described in U.S. Pat. No. 5,186,118 (Stinson); U.S. Pat. No. 7,765,863 (Woolsey); and U.S. Pat. No. 8,424,379 (Bibby). A disadvantage of this type of device is that the powder is susceptible to clumping caused by humid atmospheric conditions, and this may render the device unusable. Powder discharge devices are also messy to reload.
Electronic wind gauges are also known wherein a liquid is vaporized by energizing a heating element. Examples of this type of wind gauge are disclosed in U.S. Pat. No. 2,311,199 (Astradsson) and U.S. Pat. No. 4,326,119 (Swiatosz). Known electronic wind gauges are structurally complex and do not provide an organized stream of air for carrying the vapor into the atmosphere as a well-defined line of vapor indicating a reference direction. Unintended discharge may also be a problem if the electronic device is accidentally turned on when a user is reaching for other equipment, such as a gun or ammunition.
What is needed is a reliable, compact, easily portable wind tracking device that discharges a well-defined line of visible vapor and is not susceptible to accidental discharge.